'use strict';

/*
 * $Id: base64.js,v 2.15 2014/04/05 12:58:57 dankogai Exp dankogai $
 *
 *  Licensed under the BSD 3-Clause License.
 *    http://opensource.org/licenses/BSD-3-Clause
 *
 *  References:
 *    http://en.wikipedia.org/wiki/Base64
 *
 *  From https://raw.githubusercontent.com/dankogai/js-base64/master/base64.js 根据此改编
 */

(function () {
    'use strict';

    var global = {};
    // existing version for noConflict()
    var _Base64 = global.Base64;
    var version = "2.1.9";
    // if node.js, we use Buffer
    var buffer;
    if (typeof module !== 'undefined' && module.exports) {
        try {
            buffer = require('buffer').Buffer;
        } catch (err) {}
    }
    // constants
    var b64chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
    var b64tab = function (bin) {
        var t = {};
        for (var i = 0, l = bin.length; i < l; i++) {
            t[bin.charAt(i)] = i;
        }return t;
    }(b64chars);
    var fromCharCode = String.fromCharCode;
    // encoder stuff
    var cb_utob = function cb_utob(c) {
        if (c.length < 2) {
            var cc = c.charCodeAt(0);
            return cc < 0x80 ? c : cc < 0x800 ? fromCharCode(0xc0 | cc >>> 6) + fromCharCode(0x80 | cc & 0x3f) : fromCharCode(0xe0 | cc >>> 12 & 0x0f) + fromCharCode(0x80 | cc >>> 6 & 0x3f) + fromCharCode(0x80 | cc & 0x3f);
        } else {
            var cc = 0x10000 + (c.charCodeAt(0) - 0xD800) * 0x400 + (c.charCodeAt(1) - 0xDC00);
            return fromCharCode(0xf0 | cc >>> 18 & 0x07) + fromCharCode(0x80 | cc >>> 12 & 0x3f) + fromCharCode(0x80 | cc >>> 6 & 0x3f) + fromCharCode(0x80 | cc & 0x3f);
        }
    };
    var re_utob = /[\uD800-\uDBFF][\uDC00-\uDFFFF]|[^\x00-\x7F]/g;
    var utob = function utob(u) {
        return u.replace(re_utob, cb_utob);
    };
    var cb_encode = function cb_encode(ccc) {
        var padlen = [0, 2, 1][ccc.length % 3],
            ord = ccc.charCodeAt(0) << 16 | (ccc.length > 1 ? ccc.charCodeAt(1) : 0) << 8 | (ccc.length > 2 ? ccc.charCodeAt(2) : 0),
            chars = [b64chars.charAt(ord >>> 18), b64chars.charAt(ord >>> 12 & 63), padlen >= 2 ? '=' : b64chars.charAt(ord >>> 6 & 63), padlen >= 1 ? '=' : b64chars.charAt(ord & 63)];
        return chars.join('');
    };
    var btoa = global.btoa ? function (b) {
        return global.btoa(b);
    } : function (b) {
        return b.replace(/[\s\S]{1,3}/g, cb_encode);
    };
    var _encode = buffer ? function (u) {
        return (u.constructor === buffer.constructor ? u : new buffer(u)).toString('base64');
    } : function (u) {
        return btoa(utob(u));
    };
    var encode = function encode(u, urisafe) {
        return !urisafe ? _encode(String(u)) : _encode(String(u)).replace(/[+\/]/g, function (m0) {
            return m0 == '+' ? '-' : '_';
        }).replace(/=/g, '');
    };
    var encodeURI = function encodeURI(u) {
        return encode(u, true);
    };
    // decoder stuff
    var re_btou = new RegExp(['[\xC0-\xDF][\x80-\xBF]', '[\xE0-\xEF][\x80-\xBF]{2}', '[\xF0-\xF7][\x80-\xBF]{3}'].join('|'), 'g');
    var cb_btou = function cb_btou(cccc) {
        switch (cccc.length) {
            case 4:
                var cp = (0x07 & cccc.charCodeAt(0)) << 18 | (0x3f & cccc.charCodeAt(1)) << 12 | (0x3f & cccc.charCodeAt(2)) << 6 | 0x3f & cccc.charCodeAt(3),
                    offset = cp - 0x10000;
                return fromCharCode((offset >>> 10) + 0xD800) + fromCharCode((offset & 0x3FF) + 0xDC00);
            case 3:
                return fromCharCode((0x0f & cccc.charCodeAt(0)) << 12 | (0x3f & cccc.charCodeAt(1)) << 6 | 0x3f & cccc.charCodeAt(2));
            default:
                return fromCharCode((0x1f & cccc.charCodeAt(0)) << 6 | 0x3f & cccc.charCodeAt(1));
        }
    };
    var btou = function btou(b) {
        return b.replace(re_btou, cb_btou);
    };
    var cb_decode = function cb_decode(cccc) {
        var len = cccc.length,
            padlen = len % 4,
            n = (len > 0 ? b64tab[cccc.charAt(0)] << 18 : 0) | (len > 1 ? b64tab[cccc.charAt(1)] << 12 : 0) | (len > 2 ? b64tab[cccc.charAt(2)] << 6 : 0) | (len > 3 ? b64tab[cccc.charAt(3)] : 0),
            chars = [fromCharCode(n >>> 16), fromCharCode(n >>> 8 & 0xff), fromCharCode(n & 0xff)];
        chars.length -= [0, 0, 2, 1][padlen];
        return chars.join('');
    };
    var atob = global.atob ? function (a) {
        return global.atob(a);
    } : function (a) {
        return a.replace(/[\s\S]{1,4}/g, cb_decode);
    };
    var _decode = buffer ? function (a) {
        return (a.constructor === buffer.constructor ? a : new buffer(a, 'base64')).toString();
    } : function (a) {
        return btou(atob(a));
    };
    var decode = function decode(a) {
        return _decode(String(a).replace(/[-_]/g, function (m0) {
            return m0 == '-' ? '+' : '/';
        }).replace(/[^A-Za-z0-9\+\/]/g, ''));
    };
    var noConflict = function noConflict() {
        var Base64 = global.Base64;
        global.Base64 = _Base64;
        return Base64;
    };
    // export Base64
    global.Base64 = {
        VERSION: version,
        atob: atob,
        btoa: btoa,
        fromBase64: decode,
        toBase64: encode,
        utob: utob,
        encode: encode,
        encodeURI: encodeURI,
        btou: btou,
        decode: decode,
        noConflict: noConflict
    };
    // if ES5 is available, make Base64.extendString() available
    if (typeof Object.defineProperty === 'function') {
        var noEnum = function noEnum(v) {
            return { value: v, enumerable: false, writable: true, configurable: true };
        };
        global.Base64.extendString = function () {
            Object.defineProperty(String.prototype, 'fromBase64', noEnum(function () {
                return decode(this);
            }));
            Object.defineProperty(String.prototype, 'toBase64', noEnum(function (urisafe) {
                return encode(this, urisafe);
            }));
            Object.defineProperty(String.prototype, 'toBase64URI', noEnum(function () {
                return encode(this, true);
            }));
        };
    }
    // that's it!
    if (global['Meteor']) {
        Base64 = global.Base64; // for normal export in Meteor.js
    }
    module.exports = global.Base64;
})();